1. Field of Invention
The present invention relates to a machine tool and, more particularly, to a silent apparatus for grabbing a knife from a turret of a machine tool.
2. Related Prior Art
As disclosed in Taiwanese Patent I319343, FIGS. 3 to 10, a silent apparatus for grabbing a knife from a turret includes a power unit 30, a stationary disc 31, a shaft 32 and a rotary bar 33. The stationary disc 31 includes two recesses 39 and is placed beneath the power unit 30. The shaft 32 is operatively connected to the power unit 30 and the rotary bar 33 is attached to the shaft 32 so that the power unit 30 rotates the rotary bar 33 via the shaft 32. The rotary bar 33 includes two clasps 34 each formed at an end. This conventional apparatus further includes two locking units 40each including a latch 45, a rod 46, a first spring 41, a pusher 43and a second spring (not numbered). The latch 45 is horizontally movable on the rotary bar 33. The rod 46 includes an end connected to the latch 45 and another end for contact with the pusher 43. The first spring 41 is compressed between a portion 38 of the rotary bar 33 and a nut 48 mounted on the rod 46 so that the first spring 41 biases the latch 45 from the corresponding clasp 34 via the rod 46. The pusher 43 is vertically movable on the rotary bar. The second spring is compressed between a portion of the rotary bar 33 and the pusher 43 so that the second spring biases the pusher 43 to push the rod 46 to move the latch 45toward the corresponding clasp 34. The stationary disc 31normally pushes down the pusher 43 of each locking unit 40 by an upper end and therefore keeps a wedge of the pusher 43 from the rod 46 to allow the first spring 41 to move the latch 45 from the corresponding clasp 34. Then, the power unit 30 rotates the rotary bar 33 via the shaft 32 to bring each clasp 34 into engagement with a knife. Then, the power unit 30 rotates the rotary bar 33 into a position to admit the upper end of the pusher 43 of each locking unit 40 into a corresponding recess 39. Thus, the second spring is allowed to lift the pusher 43 to bring the wedge of the pusher 43 into contact with the rod 46. The rod 46 in turn moves the latch 45toward the corresponding clasp 34. Thus, the latch 45 and the corresponding clasp 34 firmly hold a knife.
As disclosed in Taiwanese Patent I386277, FIGS. 3 to 8, another silent apparatus for grabbing a knife from a turret includes a power unit 30, a stationary disc 31, a shaft 32 and a rotary bar 40. The stationary disc 31 includes two recesses 311 and is placed beneath the power unit 30. The shaft 32 is operatively connected to the power unit 30 and the rotary bar 40 is attached to the shaft 32so that the power unit 30 rotates the rotary bar 40 via the shaft 32. The rotary bar 40 includes two clasps 41 each formed at an end. This conventional apparatus further includes two locking units 50each including a latch 61, a length adjuster 62, a shuttle 63, a pusher 72, a connector 80, and two springs 613 and 73. The length adjuster 62 includes an end attached to the latch 61 and an opposite end attached to the shuttle 63. The latch 61, the length adjuster 62 and the shuttle 63 are horizontally movable on the rotary bar 40. The first spring 613 is compressed between a portion of the latch 61 and a screw (not numbered) secured to the rotary bar 40 so that the first spring 613 biases the latch 61 toward the corresponding clasp 41. The pusher 72 is vertically movable on the rotary bar 40. The connector 80 includes an end pivotally connected to the shuttle 63 and an opposite end pivotally connected to the pusher 72. The second spring 73 is compressed between a portion of the rotary bar 40 and the pusher 72 so that the second spring 73 biases the pusher 72 to push the latch 61 toward the corresponding clasp 41 via the connector 80, the shuttle 63 and the length adjuster 62. The stationary disc 31 normally pushes down the pusher 72 of each locking unit 40 by an upper end and therefore keeps the latch 61 from the corresponding clasp 41. Then, the power unit 30 rotates the rotary bar 40 via the shaft 32 to bring each clasp 41 into engagement with a knife. Then, the power unit 30 rotates the rotary bar 40 into a position to admit the upper end of the pusher 72 of each locking unit 40 into a corresponding recess 311 to allow the second spring 73 to lift the pusher 72 to move the latch 61 toward the corresponding clasp 41. The first spring 613 also works to move the latch 61 toward the corresponding clasp 41. Hence, the latch 61 and the corresponding clasp 41 firmly hold a knife.
As disclosed in Taiwanese Patent I397453, another silent apparatus for grabbing a knife from a turret includes a rotating unit 4, a stationary disc 41, a shaft 40 and a rotary bar 1. The stationary disc 41 includes two recesses 410 and is placed beneath the rotating unit 4. The shaft 40 is operatively connected to the rotating unit 4 and the rotary bar 1 is attached to the shaft 40 so that the rotating unit 4 rotates the rotary bar 1 via the shaft 40. The rotary bar 1 includes two clasps 10 each formed at an end. The third conventional apparatus further includes two locking units 3each including a latch 31, a length adjuster 32, a shuttle 30, a pusher 2, and two springs 33 and 21. The length adjuster 32includes an end attached to the latch 31 and an opposite end attached to the shuttle 30. The latch 31, the length adjuster 32and the shuttle 30 are horizontally movable on the rotary bar 1. The first spring 33 is compressed between a portion of the latch 31and a portion of the rotary bar 1 so that the first spring 33 biases the latch 31 toward the corresponding clasp 10. The pusher 2 is vertically movable on the rotary bar 1. The shuttle 30 includes two lugs 302. The pusher 2 includes a fin 22 that includes an inclined slot 23. The fin 22 is placed between the lugs 302. A pin 24 is inserted in the slot 23 through the lugs 302. The second spring 21is compressed between a portion of the rotary bar 1 and the pusher 2 so that the second spring 21 biases the pusher 2 to push the latch 31 toward the corresponding clasp 10 as the pin 24 slides along the slot 23. The stationary disc 41 normally pushes down the pusher 2 of each locking unit 3 by an upper end and therefore keeps the latch 31 from the corresponding clasp 10. Then, the rotating unit 4rotates the rotary bar 1 via the shaft 40 to bring each clasp 10 into engagement with a knife. Then, the rotating unit 4 rotates the rotary bar 1 into a position to admit the upper end of the pusher 2 of each locking unit 3 into a corresponding recess 410 to allow the second spring 21 to lift the pusher 2 to move the latch 31 toward the corresponding clasp 10. The first spring 33 also works to move the latch 31 toward the corresponding clasp 10. Hence, the latch 31 and the corresponding clasp 10 firmly hold a knife.
The present invention is therefore intended to obviate or at least alleviate the problems encountered in the prior art.